1.A. Field of the Invention
The explosive growth of intercommunication between computers over the Internet has created a consequential need for means to monitor networks while they are working, in order to assure that the communication flows stay within acceptable limits of both speed and quality. To assure and measure a network's connections, the communications flowing through them must be monitored and the communication flow subjected to analysis.
Monitoring and analyzing the communication flows requires both physical and logical assessment. Physical assessment must test each of the several criteria (e.g. voltage drop, baud, clarity) that define a particular connection's physical constraints; while logical assessment must similarly test each of the several criteria (e.g. routing, authorization, timing) that define a particular communication's logical constraints. Recently it has become a normal procedure to tap into the signal flow over a connection being analyzed.
One problem that had to be solved, for both electrical/copper and optical/fiber connections, was how to tap into the communication flow without interfering with the traffic that was passing through the connection being tapped. Physically, any tap potentially creates interference (either from a drop in potential or timing delay); logically, a tap could become an unsought and unwanted network termination. In perhaps no other field is the Heisenberg principle (that the act of observation changes the behavior of whatever is being observed) more keenly felt. As the signal speed and sensitivity of communications and especially computer networks increased, the interference potential from any tap also went up, in linear, locked progression.
Generally, network taps need only be consulted a small portion of the time. The problem was that every time a tap's power was turned on or off, it would send a disruptive ‘spike’ through the communications flow, interrupting the process and requiring a retransmission of the temporarily-disrupted data. Leaving a tap permanently turned on, however, both increased the power consumption of the network as a whole and put additional usage time on the tap, potentially reducing its service life. The network needed taps to be available on call rather than continuously, but also needed taps which could be powered on or off without interfering with the communications flow.
1.B. Description of the Related Art
In the field of monitoring network performance, the prior art has focused on the development, and uses, of network taps devoted to analytical purpose and monitoring of the communications flow. The stabler a network the less it needs a tap to monitor non-existent problems; yet the more taps that are tuned in can create disruptive interference and interruption when they are turned on or off.
This is particularly crucial when taps must be turned on and off to properly assess and evaluate intermittent, context-dependent, or transient signal interference effects; or identifying and prioritizing sub-network stability. It is also important in the longer context as part of an ongoing management effort to train, maintain, and sustain a continuous and uninterrupted network communications flow where the periphery and set of connections will change over time, without disrupting the overall structure and process. For these and other reasons apparent to those skilled in the art, taps needed to be such that they could be turned on and off. Yet each time they were, they created an interruption which reduced the overall network capability.
With the increase in network traffic has also come an increase in the number, and differing natures, of problems which can afflict a network. The Internet in particular uses a packet-based protocol which presumes both a constantly changing set of network connections and that each connection is only semi-dependable. Signals can be mis-addressed, mis-routed, mis-timed, disordered, degraded, or otherwise interfered with. Connections can be formed, dropped, spoofed, or otherwise be imperfect; and they definitely change over time—sometimes, over a very short time indeed. The more taps, the better the monitoring could be, but the greater the overall drain on the network's power from just the taps would be. The prior art simply accepted the “fact” that turning a tap's power on or off generated a microsecond delay, which seemed to be fine—until we reached the age of gigabit, high-speed, and broadband network transmissions.
The prior art used a switching approach to turn on and off both the power to the monitoring network tap and to redirect the communication flow through the network tap and the attached monitoring device(s). Up until now, people simply designed into their networks an acceptance that a price of using a tap was the fact that every time the tap's power was turned on or off, there would be a microsecond delay and a signal-damaging spike caused by the impedance change to the circuit as a whole as the communications flow was switched.